全文获取类型
收费全文 | 1487篇 |
免费 | 91篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 49篇 |
妇产科学 | 13篇 |
基础医学 | 179篇 |
口腔科学 | 31篇 |
临床医学 | 232篇 |
内科学 | 330篇 |
皮肤病学 | 24篇 |
神经病学 | 66篇 |
特种医学 | 241篇 |
外科学 | 129篇 |
综合类 | 34篇 |
预防医学 | 98篇 |
眼科学 | 52篇 |
药学 | 86篇 |
中国医学 | 3篇 |
肿瘤学 | 30篇 |
出版年
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 7篇 |
2019年 | 12篇 |
2018年 | 23篇 |
2017年 | 17篇 |
2016年 | 14篇 |
2015年 | 30篇 |
2014年 | 23篇 |
2013年 | 57篇 |
2012年 | 33篇 |
2011年 | 45篇 |
2010年 | 34篇 |
2009年 | 37篇 |
2008年 | 35篇 |
2007年 | 70篇 |
2006年 | 31篇 |
2005年 | 64篇 |
2004年 | 42篇 |
2003年 | 29篇 |
2002年 | 27篇 |
2001年 | 34篇 |
2000年 | 30篇 |
1999年 | 27篇 |
1998年 | 57篇 |
1997年 | 38篇 |
1996年 | 63篇 |
1995年 | 50篇 |
1994年 | 45篇 |
1993年 | 54篇 |
1992年 | 24篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 43篇 |
1988年 | 54篇 |
1987年 | 48篇 |
1986年 | 39篇 |
1985年 | 37篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 18篇 |
1981年 | 24篇 |
1980年 | 20篇 |
1979年 | 14篇 |
1978年 | 13篇 |
1977年 | 21篇 |
1976年 | 10篇 |
1975年 | 10篇 |
1969年 | 7篇 |
1912年 | 6篇 |
排序方式: 共有1639条查询结果,搜索用时 15 毫秒
61.
PB Greer K Dahl MA Ebert M White C Wratten P Ostwald P Pichler JW Denham 《Journal of Medical Imaging and Radiation Oncology》2008,52(5):517-524
The aims of this study were to investigate whether intrafraction prostate motion can affect the accuracy of online prostate positioning using implanted fiducial markers and to determine the effect of prostate rotations on the accuracy of the software‐predicted set‐up correction shifts. Eleven patients were treated with implanted prostate fiducial markers and online set‐up corrections. Orthogonal electronic portal images were acquired to determine couch shifts before treatment. Verification images were also acquired during treatment to assess whether intrafraction motion had occurred. A limitation of the online image registration software is that it does not allow for in‐plane prostate rotations (evident on lateral portal images) when aligning marker positions. The accuracy of couch shifts was assessed by repeating the registration measurements with separate software that incorporates full in‐plane prostate rotations. Additional treatment time required for online positioning was also measured. For the patient group, the overall postalignment systematic prostate errors were less than 1.5 mm (1 standard deviation) in all directions (range 0.2–3.9 mm). The random prostate errors ranged from 0.8 to 3.3 mm (1 standard deviation). One patient exhibited intrafraction prostate motion, resulting in a postalignment prostate set‐up error of more than 10 mm for one fraction. In 14 of 35 fractions, the postalignment prostate set‐up error was greater than 5 mm in the anterior–posterior direction for this patient. Maximum prostate rotations measured from the lateral images varied from 2° to 20° for the patients. The differences between set‐up shifts determined by the online software without in‐plane rotations to align markers, and with rotations applied, was less than 1 mm (root mean square), with a maximum difference of 4.1 mm. Intrafraction prostate motion was found to reduce the effectiveness of the online set‐up for one of the patients. A larger study is required to determine the magnitude of this problem for the patient population. The inability in the current software to incorporate in‐plane prostate rotations is a limitation that should not introduce large errors, provided that the treatment isocentre is positioned near the centre of the prostate. 相似文献
62.
Airway compression secondary to left atrial enlargement and increased pulmonary artery pressure 总被引:2,自引:0,他引:2
M E Dailey M P O'Laughlin R J Smith 《International journal of pediatric otorhinolaryngology》1990,19(1):33-44
Although congenital cardiac defects are infrequently considered a cause of major airway compression in neonates and infants, patients with left-sided cardiac enlargement can develop compression of the left mainstem bronchus. This is a consequence of the intimate relationship of the trachea and left mainstem bronchus to the left atrium, left pulmonary veins and left pulmonary artery. If the mean pulmonary arterial pressure, mean left atrial pressure and carinal angle are increased, the likelihood of major airway compression is high. 相似文献
63.
PURPOSE: To present the carbon dioxide laser as an effective tool for surgical debulking of eyelid and orbital neurofibromas. METHOD: Two patients with neurofibromatosis underwent surgical debulking of their eyelid and orbital plexiform neurofibromas by means of the carbon dioxide laser. RESULTS: Acceptable cosmetic results were obtained with the removal of eyelid and orbital neurofibromas with improved hemostasis and minimal destruction of surrounding tissue when compared with conventional methods of removal. CONCLUSIONS: The carbon dioxide laser may allow significant improvement in the removal of plexiform neurofibromas. 相似文献
64.
65.
Hansen JA Welsh PG Lipton J Cacela D Dailey AD 《Environmental toxicology and chemistry / SETAC》2002,21(1):67-75
Bull trout (Salvelinus confluentus) were recently listed as threatened in the United States under the federal Endangered Species Act. Present and historical habitat of this species includes waterways that have been impacted by metals released from mining and mineral processing activities. We conducted paired bioassays with bull trout and rainbow trout (Oncorhynchus mykiss) to examine the relative sensitivity of each species to Cd and Zn independently and as a mixture. A total of 15 pairs of acute toxicity bioassays were completed to evaluate the effects of different water hardness (30 or 90 mg/L as CaCO3), pH (6.5 or 7.5), and temperature (8 or 12 degrees C) on Cd and Zn toxicity. For both species, the acute toxicity of both Cd and Zn was greater than previously observed in laboratory studies. Bull trout were about twice as tolerant of Cd and about 50% more tolerant of Zn than were rainbow trout. Higher hardness and lower pH water produced lower toxicity and slower rates of toxicity in both species. Elevated temperature significantly increased the sensitivity of bull trout to Zn but decreased the sensitivity (not significantly) of rainbow trout to Zn. At a hardness of 30 mg/L, the toxicity values (i.e., median lethal concentration; 120-h LC50) for both species were lower than the current U.S. national water quality criteria for protection of aquatic life, indicating that current national criteria may not be protective of sensitive salmonids--including the threatened bull trout--in low calcium waters. 相似文献
66.
67.
PURPOSE: To compare characteristics and outcomes of strabismus surgery in patients who have undergone orbital decompression for thyroid eye disease with those who have not. SUBJECTS AND METHODS: A chart review of all patients with thyroid eye disease requiring strabismus surgery in one physician's practice. RESULTS: There were 36 patients in the decompression group (DG) and 14 patients in the no-decompression group (NDG). There was a significantly greater amount of preoperative esotropia in the DG ( P = 0.02). There was an increased incidence of A-pattern in the DG ( P = 0.09). There was a slightly higher number of operated muscles in the DG ( P = 0.005). A good or excellent outcome was achieved in 93% of the NDG and in 94% of the DG ( P = 0.83). DISCUSSION: Previous studies suggest that patients requiring orbital decompression have a more complex thyroid eye disease and a lower success rate after strabismus surgery. Our findings suggest that this is not necessarily the case, and the difference in surgical success rates between the studies may in part be due to orbital decompression technique or indication. CONCLUSION: In this series, using a fixed suture technique, outcomes of strabismus surgery in patients with thyroid eye disease who underwent orbital decompression are similar to those who did not. 相似文献
68.
Dailey GE Boden GH Creech RH Johnson DG Gleason RE Kennedy FP Weinrauch LA Weir M D'Elia JA 《Metabolism: clinical and experimental》2000,49(11):1491-1495
The purpose of this study was to assess the effects of pulsatile intravenous insulin therapy (PIVIT) on the progression of diabetic nephropathy in patients with type 1 diabetes mellitus (DM). This 18-month multicenter, prospective, controlled study involved 49 type 1 DM patients with nephropathy who were following the Diabetes Control and Complications Trial (DCCT) intensive therapy (IT) regimen. Of these, 26 patients formed the control group (C), which continued on IT, while 23 patients formed the treatment group (T) and underwent, in addition to IT, weekly PIVIT. Blood pressure in all patients was maintained below 140/90 mm Hg on antihypertensive medication, preferentially using angiotensin-converting enzyme (ACE) inhibitors. All study patients were seen in the clinic weekly for 18 months, had monthly glycohemoglobin (HbA1c), and every 3 months, 24-hour urinary protein excretion and creatinine clearance (CrCl) determinations. The HbA1c levels declined from 8.61% +/- 0.33% to 7.68% +/- 0.31% (P = .0028) in the T group and from 9.13% +/- 0.36% to 8.19% +/- 0.33% (P = .0015) in the C group during the study period. CrCl declined significantly in both groups, as expected, but the rate of CrCl decline in the T group (2.21 +/- 1.62 mL/min/yr) was significantly less than in the C group (7.69 +/- 1.88 mL/min/yr, P = .0343). We conclude that when PIVIT is added to IT in type 1 DM patients with overt nephropathy, it appears to markedly reduce the progression of diabetic nephropathy. The effect appears independent of ACE inhibitor therapy, blood pressure, or glycemic control. 相似文献
69.
JW Gregory SA Greene RT Jung CM Scrimgeour MJ Rennie 《Archives of disease in childhood》1993,68(2):205-209
Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months. 相似文献
70.